Metamodeling of Void Closure during Hot Flat Rolling

To cover the rising demand for lightweight materials, damage controlled process layout during semifinished production offers enormous potential to reduce internal damage in terms of microvoids within the material and therefore directly benefit performance and lightweight design. The closure of microvoids depends on the forming process parameters as well as their shape and relative position within the workpiece. While several models accurately describe the closure behavior of individual voids, none have yet been developed to effectively capture the closure behavior of large void distributions found in industrial material. Therefore, the present study aims to develop a fast metamodel, which allows calculating the closure behavior of large void distributions containing up to thousands of individually shaped microvoids for arbitrary hot rolling parameters. For this purpose, a method for efficiently characterizing large void distributions using light micrographs is developed. A database containing void closure data for defined reference voids and reference hot rolling parameters is generated using multiscale finite element (FE) simulations and used to interpolate the closure behavior of the experimentally determined void distribution. Results show a good agreement of the fast calculations with FE simulations for individual voids, which are not part of the database, while overestimating experimentally observed void closure.